You’ve finally got your lighting right. The mic sounds crisp. But there’s a problem: your webcam is showing your messy laundry pile in the corner, or maybe your gameplay capture has those annoying black bars on the sides. You need to know how to crop on OBS, and honestly, it’s one of those things that seems like it should be a giant button on the main dashboard, but it’s actually hidden behind a keyboard shortcut or a deep menu.
If you’re staring at a screen full of clutter, don’t panic. It happens to everyone from first-day affiliates to 20k-viewer partners.
OBS Studio is powerful, but it isn't always intuitive. Most people try to click and drag the corners of their source, only to realize they are just resizing the whole thing. That's not cropping. That's just making your laundry pile smaller and more pixelated. We want to actually chop off the parts of the image that don't belong there.
The Alt-Drag Method: The Only Way You’ll Actually Use
This is the "secret handshake" of the streaming world. If you remember nothing else from this, remember the Alt key.
Click on your source in the preview window. See those red squares (handles) on the edges? If you just click and drag them, you're scaling. But if you hold down the Alt key on your keyboard while dragging those red handles, the border turns green. Green means you're cropping. It’s that simple.
You can pull from the left, right, top, or bottom. It’s the fastest way to frame your face perfectly or remove a redundant UI element from a game. One thing to keep in mind, though: this doesn't actually change the resolution of the source. It just hides the pixels. If you crop too much and then try to stretch that tiny sliver of video back to full screen, it's going to look like a blurry mess from 2004.
When Precision Matters: The Manual Transformation
Sometimes your hand shakes. Or maybe you need two different sources to be exactly the same width, down to the last pixel. Alt-dragging is great for "eyeballing it," but for professional layouts, you need the math.
Right-click your source in the Sources dock. Hover over Transform and select Edit Transform. A window pops up that looks a bit intimidating at first, but look at the bottom. You’ll see boxes for Top, Bottom, Left, and Right. You can type in specific pixel values here.
I’ve seen streamers use this to perfectly crop out a 1080p game to fit a 4:3 ratio for retro marathons. It's also a lifesaver when you're trying to align a webcam frame over a specific overlay graphic. If the frame is 5 pixels too wide, don't struggle with the mouse. Just type "5" into the Crop: Right box. Done.
Using Filters to Crop on OBS
There is a third way. It’s a bit more "permanent" in the sense that it lives in your filter stack.
- Right-click your source.
- Select Filters.
- Click the + icon under Effect Filters.
- Choose Crop/Pad.
Why would you do this instead of just holding Alt? Usually, it's for complex scenes where you might be using the same source in multiple places. If you apply a Crop/Pad filter, it stays consistent. Also, if you want to add "padding" (adding empty space around an image), this is the only way to do it. Most people use this to create custom borders or to prepare a source for a specific effect like a blur that might bleed over the edges otherwise.
📖 Related: Why the First Picture of a Real Black Hole Still Messes With Our Heads
Common Pitfalls and Why Your Crop Looks Weird
Let's talk about the "Black Bar" nightmare.
A lot of beginners learn how to crop on OBS and then immediately make their stream look unprofessional. When you crop a 16:9 source (like most monitors) into a weird shape, you're left with empty space on your canvas. If you don't fill that space with something else—like an overlay, a chat box, or another camera angle—you’re just broadcasting black voids.
Another big one is the Bounding Box Type. In that "Edit Transform" menu we talked about, there's a setting for "Bounding Box Type." If this is set to "Scale to inner bounds," your cropped image might jump around or resize itself in ways you didn't intend. Generally, for a basic crop, you want to keep this on "No bounds" unless you have a specific reason to lock the size.
The Aspect Ratio Trap
If you're cropping a 1920x1080 source to make it a square, you're changing the aspect ratio to 1:1. That’s fine! But if you then try to "Force" that square back into a rectangular space by holding Shift while dragging, you’re going to look stretched out. Please, for the love of your viewers' eyes, don't hold Shift to stretch things. If you crop it, let it be the shape it is.
Advanced Use: The Side-by-Side Comparison
Imagine you're doing a tech review or a reaction video. You have two sources, and you want them to split the screen perfectly down the middle.
- Put both sources in your scene.
- Use the Edit Transform menu.
- If your canvas is 1920 pixels wide, you know the center point is 960.
- Crop the right side of Source A by 960 pixels.
- Crop the left side of Source B by 960 pixels.
- Align them.
Suddenly, you have a perfect split-screen that looks like it was edited in post-production, but it's happening live. This is where knowing the actual numbers beats the "Alt-drag" method every time.
Solving the "My Crop Won't Move" Issue
Sometimes you'll try to Alt-drag and nothing happens. Usually, this is because the source is locked. Check the Sources dock; is there a little padlock icon next to your camera or game capture? If it's closed, you can't change anything. Click it to unlock it.
Also, check if you have any other filters active. Sometimes a "Scaling/Aspect Ratio" filter can override your manual crops and lead to a lot of frustration.
Final Practical Steps for a Clean Layout
Start by cleaning up your webcam. Most people have way too much "headroom" (empty space above their head). Use the Alt-drag method to crop the top of your camera feed down so it's just above your hair. Then, crop the sides to remove any part of your room that doesn't need to be there. This makes your face more prominent and saves valuable screen real estate for the game or content you're actually showing.
Next, check your gameplay. If you're playing an older game that isn't widescreen, don't stretch it. Crop the black bars off the sides using the Crop/Pad filter to ensure you have a "clean" edge, then place a nice background or overlay behind it.
Lastly, always do a "test recording" after adjusting your crops. What looks good in the tiny OBS preview window might look jagged or weirdly framed when viewed full-screen on a monitor. Record 30 seconds of yourself moving around, watch it back, and adjust your pixel values in the Edit Transform menu to fine-tune the edges. This small bit of polish separates the hobbyists from the professionals.